An Improved Model of Second Virial Coefficients for Polar Fluids and Fluid Mixtures.

Abstract

A corresponding-states model was developed empirically for calculating the second virial coefficients of polar fluids and fluid mixtures. In this model, a “nonpolar” and a “polar” acentric factors characterize size/shape and polarity/association effects, respectively. The new model contains a polarity or an association parameter (αP or αHB), which can be estimated from fluid’s reduced dipole moment through a specific generalized correlation. The temperature function of association contribution was found to depend on fluid’s reduced dipole moment. This generalized model predicts well the second virial coefficients for a diversity of polar fluids and strongly hydrogen-bonded substances. The new model with a set of recommended kij’s can reasonably estimate the second virial cross-coefficients.